Today we put in a brand new MAF ($125 from the local Isuzu dealer), crossed our fingers and started him up. Started right up, idled much smoother - woohooooooo then ^(&^&&%*^ as soon as it warmed up the rpms started surging, check engine light on and flashing.. Grrrrrrrrr... Its not surging alot, but up and down between 700 and probably 1500. We took some starter fluid and sprayed it all around looking for vacuum leaks - nothing. Pulled the coils and plugs and the #2 that the code says was misfiring appeared to be burning the best although the top of the plug seemed to be oxidized. The plug itself was a milk chocolate brown. The rest of the plugs were on the light tan to almost white side.
It starts right up, no foot on the pedal and it doesn't appear to choke out or die. Just runs real rough. In the last two years I've replaced the intake manifold gasket, new egr, new idol control valve, new timing belt, plugs, water pump, had injecters cleaned and motor vacced to clean out the carbon etc. and probably a few things I've forgotten.
I'm sitting close to 138000 miles. The misfire is whats got us stumped at this point. I'm wondering if replacing the coil pack would help? Or the O2 sensors?
Thanks for help and the place to whine. As soon as I get this all figured out and paid for I'll be kicking some more $ to the site. I'm sure you guys have saved me a ton already.